1. Field of the Invention
The present invention relates to a method for manufacturing an ink jet recording head for performing recording by discharging ink. The present invention also relates to an ink jet recording head manufactured by such a method. Further, the present invention relates to an ink jet recording apparatus on which such an ink jet recording head can be mounted.
2. Related Background Art
As an example of ink jet recording heads, there is an ink jet recording head in which ink passages communicating with corresponding discharge openings are formed in a substrate. Normally, energy generating means for generating energy employed to discharge ink are disposed on a surface of the substrate in correspondence with the ink passages. Further, generally, a common liquid chamber communicating with the ink passages is provided to reserve the ink therein. In this specification, the ink passages and the common liquid chamber are referred to as "ink passages" generally. The energy generating means may be an electro-thermal conversion element or piezo-electric element which is one part of the thermal energy generating means. The substrate may, for example, be a silicon wafer.
Conventionally, methods for manufacturing such an ink jet recording head are generally divided into two groups. In the first group of methods, a negative type photosensitive resin layer is laminated on a substrate on which energy generating means are disposed, and a portion of the photosensitive resin layer corresponding to walls of a common liquid chamber and ink passages is exposed and then is developed. As a result, the resin corresponding to the partition walls between the ink passages and the like remains, but the resin corresponding to the ink passages and the common liquid chamber is removed. Thereafter, for example, a top plate or lid plate having an ink supply port in correspondence with the common liquid chamber is arranged on the partition walls. Finally, the assembly (substrate, lid plate and the like) is cut by a cutting blade while pouring a cutting liquid along a portion where discharge openings are to be formed, thereby forming a discharge opening surface (surface in which discharge opening are formed). The cutting blade may be a cutting blade used to cut the silicon wafer in a semi-conductor manufacturing process.
In the second group of methods, a positive type photosensitive resin layer is laminated on a substrate on which energy generating means are disposed, and a portion of the photosensitive resin layer corresponding to walls of a common liquid chamber and ink passages is exposed and then is developed. As a result, the resin corresponding to the partition walls between the ink passages and the like is removed, but the resin corresponding to the ink passages and the common liquid chamber remains. Thereafter, another resin is poured to cover the remaining resin and then is cured. After curing, the resin and the substrate are cut along a portion where discharge openings are to be formed, thereby forming a discharge opening surface, and by removing the remaining resin, the discharge openings and the ink passages are formed.
When manufacturing an ink jet recording head by the above-mentioned methods, since swarf often enters into the ink passages and/or the remaining resin is not removed completely by the resin removing process, so that some partly remains in the ink passages, the ink passages must be sometimes cleaned. The cleaning operation is normally performed by introducing a washing liquid into the ink passages from the ink supply port. The washing liquid may be organic solvent such as acetone, isopropyl alcohol or the like, alkali solition such as sodium hydroxide solution, detergent solution, or pure water including carbon dioxide bubbles therein.
The above-mentioned conventional ink jet recording head manufacturing methods have the following drawbacks:
(1) In the first group of methods, since the ink passages have already been opened, when the discharge openings are opened by the cutting operation, the cutting liquid including the swarf enters into the ink passages so that the swarf may sometimes accumulated on and adhere to the ink passage walls, the common liquid chamber walls and/or the surfaces of the energy generating means. Although such deposits should have naturally been removed by the cleaning process, it is not always removed completely. Further, once the ink passages are dried to solidify the remaining deposit, it is further difficult to remove the remaining deposit. If the deposits remain on the ink passages and the like, it is feared that the deposits will separate from the walls thereby to clog the discharge openings during the use of ink jet recording head. If the deposits adhere to the surface of the energy generating means, the unstable or poor ink discharge will occur.
(2) In the second group of methods, even when the cleaning process is performed, it is difficult to prevent the resin remnants which are to be removed from remaining on the walls of the ink passages (particularly, in the corners of the passages). If the resin remnants remain on the ink passages and the like, it is feared that the remnants will separate from the walls thereby to clog the discharge openings during use of the ink jet recording head. Incidentally, the reason why it is difficult to completely clean the ink passages is considered that the ink passages and the discharge openings are very small so as to have high hydrodynamic resistance and thus the flowing speed of the washing liquid cannot be great.